This invention relates to transformers in general, and particularly those type transformers employing flame retardant dielectric liquids. With the advent of recent Environmental Protection Agency banns on the use of chlorinated biphenals in transformer dielectric fluids, development programs have been undertaken on effective substitutes.
One effective substitute comprises a Silicone based oil as a dielectric coolant within those transformers used in restricted environments wherein the transformer dielectric must be relatively nonflammable. Examples of such transformers are applications in locomotive propulsion systems, electrostatic precipitative systems, and other applications within or close to habitable structures.
The use of Silicone oil in locomotive transformers requires a larger transformer housing to provide effective dielectric properties to the transformer while maintaining reliable core and coil thermal dissipation. The reason for the larger quantity of Silicone oil is the somewhat poorer thermal transfer properties apparent with the Silicone. Since Silicone oil is relatively expensive some means must be employed to increase the thermal and dielectric properties of the Silicone so that a reduced quantity can be employed without decreasing the transformer insulation.